338 fed build revisted

[stagpanther]

I built a 338 fed AR this spring based on the Wilson Combat hunter fluted and target crowned barrel. The build has overall been very frustrating in that the many loads I've tried all failed to group well--typically 2 to 4 inches at 100 yds no matter what I tried--and I tried 100's of hand-load cartridges using a wide variety of powders and bullets, but nothing showed much promise. I even called Wilson Combat and asked them to suggest a good load or factory ammo that they felt would shoot MOA or better--they couldn't (or wouldn't) make a recommendation.



Last night I was searching the load data database and stumbled across a stout load for 200 gr speer hot cors using PP 2000 MR--a powder which I recently had good results with in my 224 Valkyrie tests--but one which I would think is a bit slow for a 338 fed--but decided to give it a go anyway. The hot cors have a lead tip which unfortunately take damage when shipped apparently--consistent COLs are not really possible but otherwise they are a nice relatively short-base design--leaving lots of room for powder while still loading to standard length. They also cycle very well in an AR with no tendency (that I've experienced so far) to hang up.



The difference between this powder/bullet combination and all the other ones I've tried is extraordinary. So is the recoil force--which I would put right up there with that of a 30-06 as a result of using an uncompensated muzzle. The muzzle comes with long fluting and thus there is no option for after-market threading--my recommendation would be to get a threaded muzzle--and if you find the notion of getting pounded by an AR attractive just get a muzzle protector--but I wish I had the option of adding a brake.

[stagpanther]

Here are some of the results. This is a tough one to shoot for me--at least uncompensated--the slightest little movement is going send a flier wide--a firm shoulder weld is pretty much mandatory while anticipating the big bang and hit.

I know it's lame, but I indulged myself in tossing the obvious flier from each group ( I knew I pulled the shots as I made them) --sure made the results look a lot better. These groups are from the beginning, middle and end of the charge ladder--pretty interesting.

[bfoosh006]

Very interesting.

I would have though you would have found some accurate load

I assume you double checked some of the obvious accuracy messing things... and I know you know what you are doing.. but , just throwing some ideas out there..

GB , no contact with free float tube...ample barrel whip room ?
No contact from the ejection port retaining rod at the back of the FF tube
No binding at the gas tube to gas key.. or gas tube bottoming out in the gas key ? ( try moving the GB forward slightly )
Upper receiver face trued ?
Firing pin making consistent impacts ?
Primers fully seated , but not crushed ?

How does the throat / leade look ?... no snags at the crown ?

[stagpanther]

Thanks for the suggestions. There was in fact a bit of play between the upper and lower--as well as some looseness in the buttstock on the buffer tube when under some pressure--no doubt these factors come into play when putting some pressure on the overall system (a firm hold and pull-back). I have tightened these things (reduced "slop") up since a good hold is required to keep the weapon steady through the shot.

Wilson has it's own "intermediary" gas length system which is approximately intermediate + .75". I've got it tuned to reliably cycle moderate to warm loads but it is sensitive to the power of the cartridge.

I think the gun simply likes PP 2000MR. I'm happy to go with it as it attains both good accuracy and velocity performance. I now feel that I'm shooting "behind" the gun--in other words the limitations are due to me the shooter; instead of poor groupings that I felt was due to the gun/set-up. That's a good thing in my view.

[mulespurs]

I had a similar difficulty with an ar-15, nothing wanted to shoot well. Finally decided that the scope was the reason and traded it off.

When I took the scope off to trade it in, it had shiney spots were the rings were improperly torqued, so we had some movement in the mounts.

Once I properly tightened my rings the problem went completely away. My mounts have a stud sticking up and a ring half on each side.

You have to tighten the bottom screws first and the top ones last, just like the directions say, or the scope will flex sideways and drive you crazy when your gun and load is really ok.

Just for fun try a box of factory shells just for another test.

[stagpanther]

The single-piece mount, rings and scope are good--though they do take a fair bit of stress upon recoil after the shot, being a cantilevered mount that probably adds to the stress on muzzle-flip. I'm pretty sure the gun is now tight and shooting well--it's on me to shoot it better.

[stagpanther]

Went out again and tested some loads--more or less the same results as yesterday; 3 shots pretty close together and then a pulled flier. I've done this before with other guns that were "sensitive" to a firm hold so I'm sure it's me--not the gun.

That said, the recoil and muzzle flip are significant, so a good firm hold is necessary--free recoil off a bag rest I think may risk getting smacked in the kisser pretty hard. I hate to do any changes to the tuning or carrier system, but I'm giving some thought on reducing that recoil without a compensator.

[stagpanther]

decided to swap out a tubbs flat spring and kinetic buffer from one of my other (lesser recoiling) builds.

[gshayd]

I plan on using my .AR 10 in 338 Federal for Hunting. 1 " MOA or under is good for me. I have a Black Hole Barrel with a recoil brake.

[stagpanther]

gshayd
Senior Member

Join Date: May 14, 2017
Posts: 112
I plan on using my .AR 10 in 338 Federal for Hunting. 1 " MOA or under is good for me. I have a Black Hole Barrel with a recoil brake.

I used to love black hole before they went big time--that's why I like AR performance now. I think having the target crown does help marginally with the accuracy vs a brake--but the work needed to keep it steady--plus the recoil force--I think is a bit out of proportion to the small gain--a brake is really a good idea. I also built a 358 win AR that I put a Kahntrol brake on and it will shoot high power 225 gr pro hunter loads quite comfortably--and sub MOA.

[flashhole]

You might try setting two targets, one beside the other, and alternating shots at each target. This may provide some insight to the flier. The ammo is being fed from different magazine locations, right side, left side, right side, left side. It might make a difference.

[stagpanther]

Basically--what I've figured out is the more pressure you use to hold an AR--the more loose fitment areas come into play affecting the fall of the shot. Gaps between upper and lowers--play in pivot pins--play in buttstock; all of those things can induce a shift in the bore while breaking the shot if not held constant.

[bfoosh006]

This... just like bedding a bolt action.. an AR has its same issues at the "slop" in upper to lower fitment and stock.

I used to use plastic shims to tighten up everything... but that company went out of business and was stealing CC info... should have bought a crap load of the shims when I could have.

I strive for snug fitting uppers to lowers... just so I don't have to make sure I am using good form 100%

[gshayd]

How did BHW go big time? Columbia River Arms has always been the parent company of Black Hole Weaponry. Right now they have moved to a new facility.

https://view.joomag.com/american-pat...16725282?short

[stagpanther]

In the early days they catered to the home builder taking orders for "unusual calibers" and provided generally great shooting barrels. As time went on and commercial orders became a bigger part of their business, they expanded and that became a major part of their business. Nothing wrong with success--but my feeling was "the small guy" got lost in the shuffle. AR15 Performance, for example, provides the kind of personal attention and dedication to the small guy that I used to get from BHW. I also have done business with McGowen barrels and have been extremely impressed with their willingness to work closely with the customer to provide me with what I want--even if it was a request for a one-off designed barrel that otherwise might not be a "economy of scale batch production run of standardized specifications."

[gshayd]

I am a single shooter and don't buy that many barrels. I buy barrels from different companies. I don't feel that I have gotten lost in the shuffle. I go to the website order it the way I want it. Most of the time they start mine from scratch if they don't have some in stock for popular barrels. Yes, you have to wait sometimes. If they were just making them quickly I might get worried then. Have you ever e-mailed them and asked for a barrel you want to make a certain way.

FAQ: If you do not see what you want please CLICK HERE to drop us a note.

https://columbiariverarms.com/contact-us/

[stagpanther]

I am a single shooter and don't buy that many barrels. I buy barrels from different companies. I don't feel that I have gotten lost in the shuffle. I go to the website order it the way I want it. Most of the time they start mine from scratch if they don't have some in stock for popular barrels. Yes, you have to wait sometimes. If they were just making them quickly I might get worried then.

The important thing is that you are satisfied with your service with them. I've never been dissatisfied with the quality of their barrels--except one--which Carl immediately made right on. Like I said--I got caught in some transition issues which left me in a place that I wasn't accustomed to with them.

[gshayd]

I have taken a 6mm Creedmoor and a 6.5 Creedmore Ruger Predator Barrel and Action into an MDT Chassis and added a Luth AR MBA-3 buttstock. I know that the barrels will eventually start to shoot a bigger MOA group. I asked them about barrels for the Predators. The nice fellow replied that they did not make them but if I was willing to send the current barrel they would make me one for $300. Which I don't think is a bad price for building a one-off barrel. They also built me a .338 Federal Barrel. Yes, I got it threaded and put a brake on it. if you look at the ballistic info for a 7mm Rem Mag the .338 Federal is not too far from it with the 180 gr bullet however it has about 5 ft lbs less recoil.

[stagpanther]

I have taken a 6mm Creedmoor and a 6.5 Creedmore Ruger Predator Barrel and Action into an MDT Chassis and added a Luth AR MBA-3 buttstock. I know that the barrels will eventually start to shoot a bigger MOA group. I asked them about barrels for the Predators. The nice fellow replied that they did not make them but if I was willing to send the current barrel they would make me one for $300. Which I don't think is a bad price for building a one-off barrel. They also built me a .338 Federal Barrel. Yes, I got it threaded and put a brake on it. if you look at the ballistic info for a 7mm Rem Mag the .338 Federal is not too far from it with the 180 gr bullet however it has about 5 ft lbs less recoil.

That's sounds cool. My interest in the 338 fed is that it emulates more or less a somewhat more efficient 358 win to me. In other words--it throws the big bullets a bit further with a bit less drop with about the same energy.